Radio shielding sealing gasket



Patented Nov. 23, 1948 UNITED sTArEs PATENT' .OFFICE 2,454,567 RADIO 'smi-:Lomo SEALING GASKET Adrian A. Pierson, Jr., Cooperstown, N. Y.

Application August 2, 1944, Serial No. 547,746

1 Claim.

In the ignition system of internal combustion engines used in airplanes, motor vehicles and the like high tension current passes within the distributor in the form of a spark between a central or main terminal and a terminal for each cylinl.

der in the engine. These terminals are enclosed in the distributor body by a cap which lits thereover and, in the case of airplanes, both the body and cap are of metal. To prevent interference with the radio With which such vehicles are equipped it is necessary to prevent the waves generated by these sparks from passing outside of the distributor. Furthermore, it is not only essential that entrance of water between the cap and body of the distributor be prevented but also air leakagefrom the interior of the distributor, because the air pressure within the distributor used in planes that rise to high altitudes must be maintained substantially higher, by supercharging, than the pressure of the circumambient air.

To place between the body and the cover of the ignition distributor a gasket of the ordinary type formed of non-electrical conducting material and l which is firmly compressed between the cap and 'radio equipment. Hence, in order to prevent the entrance of moisture or the loss of the air under pressure from the inside of the distributor as well as to prevent interference with the radio equipment it is necessary to provide not only a gasket which can be compressed between the body and cap of the distributor so as to form an air and water tight seal therebetween but also one which will provide a good and substantially continuous electrical connection between said body and cap. f

It has heretofore been proposed to form such a gasket by applying a close helical wrapping or winding of wire about a single strand of natural or artificial rubber, or like substance, which is molded about a wire core. Such gaskets are comparatively expensive because of production costs and, in my copending application Serial No. 538,- 474 I have described and claimed an improved type of gasket which is considerably cheaper to manufacture and just as eiective as the gasket above described. l

My present invention involves further improvements in gaskets of this type whereby they may be very cheaply produced by rolling or extruding processes or partly by rolling and partly by extruding.

In the drawing-- l Figs. 1, 2. and 3 are very greatly enlarged cross sections of my improved type of gasket showing several diierent types of central element which form a part thereof;

Fig. 4 is a fragmentarytop or bottom view of the gasket shown in either Figs. 1, 2 or 3, and drawn to the same scale;

Fig. 5 is a fragmentary, enlarged, left side, elevation view of the coreor central element shown in Fig. 1;

Fig. 6 is an enlarged, fragmentary, vertical section of the cap and casing of a distributor employed in the ignition system of an internal combust-ion engine; and

Fig. 7 is a fragmentary, enlarged, perspective view of another form of central or core element.

In connection with the drawings it must be understood that, for clearness, the drawings are made to a very greatly enlarged scale and that, in practice, the actual cross section of the gasket is only about 1/8 inch square.

Referring to the drawings, my gasket comprises a yielding and preferably resilient metal core element, indicated generally by the numeral i and which may be of aluminum, stainless steel or other metal having inherent high resistance to corrosion or endowed with such resistance by an appropriate plating. The function of this element is to provide an electrical connection between the cap and the body of the distributor in order to prevent the passage of Waves of radiant energy therebetween. Therefore, I prefer so to shape the central metal element that ange-like surfaces thereof having fairly large areas are exposed at the top and bottom surface of the gasket so that a good electrical Contact will be made between the element and the -cap and body of the distributor. Between the flange-like portions of the central element which are exposed at the top and bottom of the gasket it may takevarious shapes such as shown in Figs. l, 2, 3 and 7; the idea being so to shape the web between the exposed flanges that it will give slightly when subjected to compressive stresses applied to the flanges such as will exist when the gasket is positioned between the cap and body of the distributor which are iirmly clamped together. If it is so designed that it will give a few thousandths of an inch when compressed without exceeding the elastic limit of the material it will be sufficient.

For this reason the web between the exposed ilanges is preferably bent as, for example, in Fig. 1 in whichthe central element has the general shape of a Greek sigma; in Fig. 2 the central element has the general shape of the Roman letter I with a bend in the vertical portion thereof; and in Fig. 3 the central element has two bends in the web. The core elements shown in Figs. l, 2 and 3 may be made either by rolling a narrow strip of thin metal between appropriate rolls or by extruding or pulling it through a die of the desired shape. Before forming the core element the strip is punched to provide staggered openings, such as 2 in the upper half and 3 in the lower halt, as illustrated in Fig. 5. The purpose of these openings is to permit .the air, oil and water impervious, material 4, which is preferably a synthetic rubber such as fneoprene" which is homogeneous and which is molded against the sides of the central element to pass through the openings in the central element as shown at 5, l and 'l so that the material on either side of the central element is rmly secured thereto as one integral piece.

in Fig. l I have shown a modieol type of core element whichcan be formed by extruding or pulling a thin strip of metal through a die which will give it the shape shown. Here a dovetailed groove is formed which is open on one side o the element and two similar grooves il and [l0 are formed on the opposite side ci the element., Thus, when the air, water and oil impervious material is molded against the side of the core it will become interioclrecl with the core by being pressed into the dovetailed grooves.

Since material like natural or articial rubber cannot be compressed and the gasket is usually confined in a recess in. the distributor cap, such as illustrated at i l, small cut out portions i2 are provided on opposite sides of the gasket to pro= vide space into which the material fl may now when the gasket is compressed.

From the foregoing it will be apparent that.

the core element i may be made in many dierent shapes, it being necessary only to provide good electrical contact between the cap and the casing of the distributor and an element of such shape that it will give slightly under compressive stress without exceeding the elastic limit of the material. Thus, when the gasket is positioned and compressed between the cap and the body oi the distributor the central element provides a continuous electrical connection all around between the cap and body oi the distributor while material at each side of the central element, which is also compressed, prevents passage of oil, water or air between the cap and body oi' the distributor.

What I claim is:

A radio shielding sealing gasket comprising a centrally disposed metal element having portions of substantial area exposed throughout the top and bottom, respectively, of said gasket, a yieldable portion electrically connecting said exposed portions and adapted to give slightly under compressive stress applied to the top and bottom of said gasket, and a resilient, homogeneous substance secured to the opposite sides of said metal element and coextensive therewith adapted to form an air and water tight seal between two spaced elements when said gasket is compressed therebetween.

ADRIAN A. PIERSON, Jn.

REFERENCES CHTED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREGN PAI'ENTS Country Date Great Britain June 21, 1938 Number Number 

